Apparatus for wheel manufacture for correcting rotational non-uniformity of a pneumatic tire and wheel assembly

ABSTRACT

A method and apparatus for forming bolt and center-pilot mounting openings in vehicle wheels, particularly styled-disc vehicle wheels. A preformed rim and disc assembly is engaged and fixtured around the rim bead seat with the inboard disc face resting on a lower die assembly and without plastic deformation to the rim or disc. An upper die assembly having an array of bolt hole punches is moved into piercing-and-coining engagement with the disc to form the bolt openings continued motion of the upper die assembly against the wheel disc pushes the disc and lower die assembly into shearing engagement with a center punch which forms the center-pilot opening. The axes of the bolt openings and/or center pilot opening and/or bead seats may be aligned or offset from each other.

This application is a continuation-in-part of application Ser. No.667,338 filed Nov. 1, 1984, now abandoned.

The present invention relates to the art of vehicle wheel manufacture,and more particularly to correction of variations in the radial runoutand/or radial force variations in a pneumatic tire and wheel assembly.

BACKGROUND OF THE INVENTION

A problem long-standing in the art lies in the production of pneumatictires and wheels which, when assembled and operated on a vehicle, runtrue about their axis of rotation. Forces generated by anycircumferential variations in the tire carcass and/or out-of-roundcondition in the tire or wheel cause vibraions, which in turn lead todissatisfied customers and significant warranty claims againstautomobile manufacturers. The present trend among manufacturers towardhigher tire inflation pressures and smaller vehicles to improve fueleconomy accentuates this problem, so that uniformity of radial runoutand force vibrations of the tire and wheel assembly has become morecritical than in the past.

Vehicle wheels conventionally include a circular array of disc boltopenings adapted to receive mounting studs for mounting the wheel to avehicle, and a center-pilot opening adapted to be received over thewheel hub. It has been and remains conventional practice in the industryto attempt to form the bolt mounting circle and center-pilot openingsco-axially with each other and with the tire rim bead seat, with thegoal thus being a perfect true-running wheel. A number of techniqueshave been proposed for accomplishing this result, including formation ofthe bolt and center openings with a single tool while locating off ofthe bead seat, machining the center opening while locating off of thepre-formed bolt-mounting openings, and/or circumferentially permanentlydeforming the rim bead seats while locating off of the bolt-mountingand/or center-pilot openings.

Gregg U.S. Pat. No. 3,688,373 discloses apparatus for rounding andforming vehicle wheels. A disc and rim assembly having preformed boltand center openings is fixtured in a die by pins received into the boltopenings. With the bolt-hole circle so located, rim-rounding dies arereciprocated against the rim bead seats, which are initially oversize,to plastically deform the bead seats with respect to the fixturedbolt-hole circle. With the wheel so deformed and clamped, additionalsizing may be performed on the bolt holes by supplemental punches, andthe center opening may be deformed by bringing the clamped rim and discagainst a center-hole forming tool.

The machine and process disclosed in the Gregg patent suffer from anumber of deficiencies in both theory and practice. First of all, it isnot possible to locate the bead seat axis, and/or to control radialrunout from the average bead seat axis, employing a rim-deformationprocess of the character disclosed to accuracy currently specified byindustry standards. Secondly, elasticity in the rim and disc precludeaccurate location of either the bolt or center opening axis with respectto the average bead seat axis, let alone accurate location of bothopening axes with respect to the average bead seat axis and with respectto each other. Thirdly, it is extremely difficult in the formingapparatus disclosed in Gregg to vary the location of the bead seat,bolt-hole and center-opening axes with respect to each other.

A particular problem is encountered in connection with so-called styledwheels which possess a deep-drawn neck or cone integrally projectingfrom the disc surrounding the center-pilot opening to simulate a styledhub cap. It is conventional practice in manufacture of such wheels tomachine the inside surface or ID at the base of the styled neck or conewhile locating off of the bead seats to obtain concentricity between thecenter opening and bead seats. Such a separate machining operation isexpensive to implement and tends to weaken the disc structure at thebase of the styled center cone.

Daudi et al U.S. Pat. Nos. 4,279,287 and 4,354,407, both assigned to theassignee hereof, depart from the conventional practice of attempting toform a true-running wheel, and address the problem of radial runoutand/or radial force variations in a pneumatic tire and wheel assembly byintentionally forming the bolt-mounting and/or center-pilot openings inthe wheel disc at the time of wheel manufacture on an axis which iseccentrically offset from the average axis of the bead seats on thewheel rim. This offset is in a direction and amount which ispredetermined to locate the low point or high point of the firstharmonic of beat seat radial runout circumferentially adjacent to aselected location on the wheel rim. In the preferred embodiments, thelow point of the first harmonic of bead seat radial runout liessubstantially within a quadrant centered about the valve hole in therim. A pre-tested tire having the location of the high point of thefirst harmonic of radial force variation marked thereon may then beassembled onto the wheel such that the respective tire and wheelharmonics are complementary and thereby tend to cancel each other.

In the preferred wheel forming apparatus disclosed in the above-notedDaudi et al U.S. patents, the bolt and center-pilot openings are formedby separate punches fixedly mounted on a single punch assembly whichsimultaneously punch-forms all of the openings in a wheel disc while thewheel is located by fixturing the same about the rim bead seats.Although the method and apparatus disclosed in the reference patents, aswell as the wheels formed thereby, have enjoyed substantial success andacceptance in the art, a problem lies in the fact that the relationshipof the bolt hole circle and center-pilot opening with respect to eachother is fixed at the time of die manufacture and cannot be readilyadjusted thereafter. Another problem is encountered in connection withapplication of this technology to manufacture of styled wheels whereinthe center-pilot surface at the base of the styled disc cone cannot bereadily formed while the bolt hole openings are formed.

OBJECTS AND SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a methodof manufacturing a vehicle wheel of the described type wherein thecenter-pilot and bolt-mounting openings are accurately and adjustablypositioned with respect to each other and with respect to the averageaxis of the rim bead seats, as well as to provide an apparatus forperforming such method and a wheel resulting from application thereof.

A further and yet more specific object of the invention is to provide aneconomical and accurate method of locating the axis of the center-pilotopenings and/or the rim bead seats, and to provide an apparatus forperforming such method as well as a wheel resulting from implementationthereof.

A further object of the invention is to provide a wheel manufacturingmethod and apparatus which is economical to implement in mass productionof vehicle wheels.

It is yet another object of the invention to provide a method andapparatus of the described character wherein the location of the centerof the bolt-hole circle, the axis of the center-pilot opening, and theaverage axis of the rim bead seats are all adjustable with respect toeach other, so that the method and apparatus of the invention may beimplemented in manufacture of true-running wheels wherein all axes andcenters are nominally concentric, or in the manufacture of wheels inaccordance with the above-referenced patents wherein the low point orhigh point of the first harmonic of average bead seat radial runout iseccentrically offset with respect to either or both of the bolt orcenter-pilot openings in the wheel disc by an amount and in a directionpredetermined to locate the low point or high point of the firstharmonic of bead seat radial runout circumferentially adjacent to aselected location on the wheel rim.

In summary, the foregoing and other objects of the invention areaccomplished by forming the bolt and center-pilot openings at separatestages of a continuous machine motion against the disc of a preassembledrim and disc while the rim is fixtured and located, but not deformed,around the bead seats. The wheel forming apparatus in accordance withthe preferred embodiment of the invention includes a planarcircumferential array of jaws mounted for radial reciprocation intoengagement with the rim bead seats to fixture and hold a preassembledrim and disc, and thereby define an average bead seat axis. Preferably,the jaws engage the bead seats around less than fifty percent of the rimcircumference. It is critical that no plastic deformation results fromthis fixturing process, both because of the aforementioned problem ofaccurately locating the various axes simultaneously with such plasticdeformation, and because plastic deformation around less than the entireperiphery would scar the bead seats and create unacceptable rimundulations. Portions of the forming apparatus which engage the discduring the rim-fixturing process are designed to accommodate limitedlateral motion of the rim and disc assembly, so that the average beadseat axis is controlled by the rim-engaging jaws without stressing ordeforming the disc.

An upper die assembly is mounted above the planar jaw array and includespunches for piercing and coining the bolt-mounting openings in a wheelfixtured by the jaws. A lower die assembly is mounted beneath the jawarray to engage and hold the wheel disc as the bolt openings arepierced. The lower die assembly and the circumferential jaw array arecarried for conjoint downward motion about a fixed center column underpressure from continued downward motion of the upper die assemblyagainst the wheel disc. A swage punch is mounted on the upper end of thefixed center column to engage and form the center-pilot opening as thedisc is carried downwardly thereagainst by the die assemblies.

The axis of the center column and the conjoint axis of reciprocation ofthe upper and lower die assemblies (nominally) define the axis of thebolt-hole circle formed in the wheel disc. The jaws which locate theaverage bead seat axis are individually adjustable with respect to thedie axis, so that the average bead seat axis and bolt hole axis may bealigned, or may be laterally offset as taught by the above-referencedDaudi et al patents. Likewise, the axis of the punch on the centercolumn is laterally selectable with respect to the column/die axis toaccommodate coaxial positioning of the center-pilot opening with theaverage bead seat axis, and/or alignment with the bolt-opening axis,and/or eccentric offsetting from both. Preferred embodiments of thepreformed rim and disc assembly include radial deformation or ledgesaround the disc center opening which are sheared by the swage punch.Deformation of the disc body and consequent misplacement of the centerhole axis is thereby minimized. One embodiment of the shear punchincludes a stripper for removing sheared material.

Operation of the invention thus in general contemplates fixturing of apreformed disc and rim so as to locate the average bead seat axis. Afirst or upper die assembly having bolt-opening punches mounted thereonis brought into engagement with the disc while a second or lower dieassembly engages the opposing disc face to support the same as the boltopenings are formed. Continued downward motion of the upper die assemblyafter forming the bolt openings pushes the lower die, bead seat locatorsand wheel downwardly against a fixed punch which engages the wheel discand forms the center-pilot opening. Time lags, incorporated as lostmotion in the forming apparatus, permit the wheel to settle intoposition between successive fixturing and forming operations.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with additional objects, features and advantagesthereof, will be best understood from the following detaileddescription, the appended claims and the accompanying drawings in which:

FIG. 1 is a fragmentary outboard elevational view of a vehicle tire andwheel assembly which includes a styled vehicle wheel manufactured inaccordance with the present invention;

FIG. 2 is a fragmentary inboard elevational view on an enlarged sale ofthe bolt and center-pilot opening region in the wheel of FIG. 1;

FIG. 3 is a sectional view of the wheel of FIG. 1 taken substantiallyalong the line 3--3 of FIG. 1;

FIGS. 4--7 are fragmentary sectioned elevational views of apparatus forforming the bolt and center-pilot openings in the wheel of FIGS. 1--3 atrespective successive states of operation;

FIG. 8 is a fragmentary sectioned elevational view of a modifiedapparatus in accordance with the invention for forming bolt andcenter-pilot openings in an alternative wheel configuration;

FIG. 9 is a fragmentary sectional view taken substantially along theline 9--9 in FIG. 8;

FIG. 10 is a fragmentary sectional view taken substantially along theline 10--10 in FIG. 2;

FIG. 11 is a sectioned elevational view bisecting modified apparatus forforming wheel mounting openings in accordance with the invention.

FIG. 12 is a fragmentary plan view of the apparatus of FIG. 11 with theupper die assembly withdrawn;

FIG. 13 is a fragmentary view on an enlarged scale of that portion ofFIG. 11 contained within the circle "FIG. 13";

FIG. 14 is a flow chart illustrating operation of the apparatus of FIGS.11-12;

FIG. 15 is a plan view of a center hole punch which may be employed inthe apparatus of FIGS. 4-7;

FIG. 16 is a plan view of the center punch and eccentric shimarrangement shown in FIG. 8;

FIGS. 17A and 17B are graphs which illustrate results obtained inlocating center-hole and bolt-hole axes with respect to each other andwith respect to average bead seat axis in accordance with the invention;

FIG. 18 is a fragmentary sectional view on an enlarged scale showing thebolt and center-opening region in a modified preformed wheel rim anddisc assembly prior to center and bolt-hole formation;

FIG. 19 is a fragmentary view taken from the direction 19 in FIG. 18;and

FIG. 20 is a view similar to that of FIG. 18 showing the wheel aftercenter and bolt hole-formation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a pneumatic tire and wheel assembly 10 as comprisinga pneumatic tire 12 pretested for variations in radial force underdynamic operating conditions and having the circumferential location ofa peak of the first harmonic of radial force variation marked at 14 onthe tire sidewall. Tire 12 is mounted on a wheel 16. Referringcollectively to FIGS. 1-3 and 10, wheel 16 includes a wheel rim 18having inboard and outboard bead seat regions 20, 22 for receivingrespective inboard and outboard bead toes of tire 12 in the usualmanner. Bead seat regions 20, 22 define an average bead seat axis whichmay be located using conventional test techniques.

A wheel mounting disc 24 is affixed to and internally spans rim 18 formounting wheel 16 and assembly 10 on a vehicle. In the ornamentalvehicle wheel illustrated in the drawings, disc 24 includes acircumferential series of radially directed axially raisedspoke-simulating portions 26 which extend from the disc peripheralflange 28 radially inwardly to a hubcap-simulating cone 32 whichsurrounds the disc center opening 30. Raised spoke-simulating discportions 26 are circumferentially separated from each other by theradially directed axially inwardly depressed disc portions 34, whichlikewise extend from flange 28 to cone 32. Bolt openings 36 are formedin a circular array, one within each of the depressed disc portions 34adjacent to cone 32 in a corresponding, slightly raised, bolt holeisland 37. Bolt openings 36 are circularly arrayed on a bolt-circleaxis. Each of the depressed disc portions 34 terminates in a radiallyinwardly directed shoulder 40 (FIGS. 2 and 10) which collectively definethe center-pilot opening which is received over and pilots wheel 16 on aspindle hub 38, as illustrated in phantom in FIG. 3. Hubcap-simulatingcone 32 projects integrally axially outboard from shoulders 40surrounding center opening 30.

In accordance with the present invention, an arcuate radially inwardlydirected land 42 is formed on each shoulder 40, with the several lands42 being on a common imaginary cylinder of revolution which defines theeffective axis of center opening 30. Lands 42 are preferably formedfollowing assembly of wheel 16 so as to place the axis of center-pilotopening 30 at a predefined relationship with respect to the average axisof bead seat regions 20, 22 and/or the axis of the circle of boltopenings 36. Such pilot axis may be nominally concentric or coaxial withthe average bead seat axis and/or the bolt-hole circle axis, or may beradially offset from either or both of such axes in accordance with theteachings of the Daudi et al patents noted hereinabove. Where one orboth of the center-pilot and bolt-opening axes are intentionallyeccentrically offset from the average bead seat axis, it is preferred tolocate a peak of the first harmonic of radial runout adjacent to thewheel valve opening 44 (FIGS. 1 and 3). Tire indicia 14 is then locatedin assembly in radially adjacent alignment with the valve hole 44 sothat the intentionally-created first harmonic of wheel radial runouttends to cancel the first harmonic of radial force variation of thetire.

FIGS. 4-7 illustrate apparatus 50 for forming bolt and center-pilotmounting openings in the wheel of FIGS. 1-3 and 10. Apparatus 50includes an upper die assembly 52 having a base 54 coupled to ahydraulic or mechanical drive (not shown) for driving upper die assembly52 in a vertical reciprocating motion. A plurality of bolt-openingpunches 56 are affixed to base 54 in a downwardly dependently orientedcircular array concentric with the axis of vertical reciprocation. Eachpunch 56 includes a substantially cylindrical tip 58 for piercing a boltopening in a wheel disc, a base 60 affixed to the die base, and anintermediate conical shoulder 62 which engages the disc subsequent topiercing of the bolt openings by tip 58 and coins the outboard edge ofthe pieced bolt openings. A die head or stripper 64 is mounted forlost-motion axial movement on base 54 at the lower face thereofsurrounding punches 56. A plurality of coil springs 66 normally biashead 64 downwardly of base 54 to the position shown in FIG. 4 of thedrawings. The lowermost portion of head 64 is contoured as at 68 toengage the wheel disc surrounding the raised bolt-hole islands 37, andis apertured to receiver wheel disc cone 32 and permit passage of bolthole punches 56 therethrough.

A cylindrical column 74 is mounted to a fixed lower base 75 and projectsupwardly therefrom coaxially with the vertical axis of reciprocation ofupper die assembly 52. A swage punch 76 is mounted by bolts 77 on theupper end of column 74. The diameter of swage punch 76 is less than thediameter of column 74, with the upper end of column 74 having a flatupper surface 80 perpendicular to the axis of die reciprocation ontowhich punch 76 is mounted. A lower die assembly 82 is mounted for guidedaxial sliding motion on and with respect to fixed center column 74.Lower die assembly 82 includes a lower die base 84 having a center bore86 received over column 74 and radially inwardly oriented shoulders 88in sliding engagement therewith. Die assembly 82 has a planar uppersurface 90 perpendicular to the axis of die reciprocation and adapted toreceive a wheel disc on the mounting surface thereof defined by adepressed circular shoulder 39 surrounding each raised bolt hole island37. In the initial position of lower die assembly 82 illustrated in FIG.4, disc mounting surface 90 is co-planar with the upper surface of punch76.

A circumferential array of buttons 92 is mounted on lower die assembly82 and these buttons project upwardly from surface 90 so as to beindividually received from the inboard direction within the pocketsdefined by wheel disc islands 37. A shoulder 94 slidably engages punch76. A plate 99 surrounds die assembly 82 and carries a pair of parallelrails 98 on opposed sides of column 74. Plate 99 is suspended by anarray of arms 97 (FIGS. 4 and 12) from hydraulic springs 96 (FIGS. 4 and11) which normally has rails 98 above the upper surface of punch 76. Diebase 54 carries and array of pins 95 which urge springs 96 downwardly,and thus reciprocate plate 99 and rails 98 with respect to die assembly82.

A circumferential array of jaws 100 are slidably mounted for conjointradial reciprocation on a planar surface 101 of lower die assembly base84 perpendicular to column 74. Each jaw 100 includes a pair of horns102, 104 contoured for engagement from the outward radial direction withthe outboard and inboard bead seats of the preassembled rim and disc.Most preferably, the wheel-engaging positions of the several jaws 100are individually adjustable. Jaws 100 are each carried by a support 200(FIGS. 11 and 12) slidably received in a radial bearing 202 on die base84. Bearing 202 thus forms a guideway for motion of support 200 and jaw100 radially of column 74. A shaft 204 is affixed by the pin 206 (FIG.11) to support 200 and projects radially therefrom slidably through aspring block 208 affixed to the upper surface of die base 84. A coilspring 210 is captured in compression between block 208 and the jam nuts212 threaded onto the radially outer end of shaft 204 for normallybiasing support 200 radially outwardly with respect to column 74. A pairof cam rollers 214 are rotatable on shafts 216 within a slot 218adjacent to the upper radially outer edge of support 200. All jaws 100and jaw supports 200 are identical.

Upper die assembly 52 is coupled to a controlled mechanical or hydraulicram 220 (FIG. 11) for reciprocal motion in the axial direction. Acircumferentially continuous actuator ring 222 (FIGS. 11 and 12) isaxially slidably carried by a circumferential array of keepers 224 whichare affixed to and project upwardly from die base 84, and is biasedupwardly with respect to die base 84 by an array of coil springs 226.Keepers 224 each have an enlarged annular head 228 which cooperates witha counterboard opening 230 in ring 232 for limiting upward motion ofring 222 with respect to base 84. Each spring 226 is captured incompression between a spring cap 232 affixed to ring 222 by the bolts234, and a spring locator pin 236 threaded onto base 84 and projectingupwardly therefrom into the spring coils. Orthogonally spaced fingers240 integrally project outwardly from the body of ring 222 and slidablyembrace corner guide post 242 for guiding motion of ring 222. Die base84 is likewise slidably guided by corner posts 242. Corner posts 242 areaffixed to and project upwardly from base 75.

A plurality of circumferentially spaced actuator blocks 244 have shanks246 slidably carried by and projecting inwardly from ring 222 inrespective alignment with rollers 214 on the several jaw supports 200.Each block 244 has a pair of angulated or ramped lower inside surfaces248 for engaging a corresponding roller 214 and urging the associatedsupport 200 and jaw 100 radially inwardly during initial downward motionof ring 222, and radially facing surfaces 250 for permitting additionaldownward motion of ring 222 without corresponding radial motion of jaws100 either inwardly or outwardly. A screw 252 extends through a block254 affixed to ring 222 and is threadably received into shank 246 ofactuator block 244 for adjusting radial position of each activator block244 with respect to ring 222, and thereby adjusting the radially inwardposition of the associated jaw 100 with respect to the remaining jawsand with respect to the axis of column 74. An abutment 256 is affixed toand depends from upper die base 54 for engagement with ring 222.Pneumatic (nitrogen-filled) springs 257 bias die base 84 upwardly withrespect to fixed base 75 and stops 255. Abutment columns 258 are carriedby base 84 for downward-driving engagement with abutment 256.

In operation, a disc wheel is preformed so as to include rim 18 havinginboard and outboard bead seat regions 20, 22, and a wheel mounting disc24 carried interiorly of the wheel rim. The rim and disc illustrated inthe drawings are preferably separately formed to the contours shown inany suitable blanking, bending, rolling and/or forming operation, andare joined to each other as by welding or the like where the outerperiphery 28 of wheel disc 24 engages the inner surface of rim 18.Apparatus 50 receives such a preformed rim and disc manually or in anautomated operation for the purpose of forming the bolt and center-pilotmounting openings therein. Preferably, in the embodiment shown in FIGS.11 and 12, with the upper die assembly fully retracted, a preformedwheel is slidably conveyed on its inboard rim edge along rails 300 ontorails 98. Upper die assembly 52 is then moved downwardly (from aposition not shown) through the position of FIG. 4 toward the positionof FIG. 5. In FIG. 4 pins 95 have engaged springs 96 and have begun tourge plate 99 and rails 98, and the wheel carrier thereof downwardlytoward lower die assembly 82. However, and in accordance with animportant feature of the present invention, stripper 64 does not contactthe wheel at this point so that the wheel is free to slide on rails 98.Continuous downward motion of upper die assembly 52 moves the inboarddisc face against lower die assembly surface 90, and then engages ring222 (FIGS. 11 and 12) to close jaws 100 to engage or chuck the rim beadseats (FIG. 14).

The preformed rim and disc is thus positioned on lower die assemblysurface 90 with buttons 92 received within the pockets of bolt holeislands 37. Preferably, as shown in greater detail in FIG. 13, head 64and buttons 92 are contoured with respect to disc islands 37 so thatthere is adequate space or clearance to accommodate positioning of thedisc and rim assembly over the desired tolerance range when jaws 100close and engage the rim bead seats. Jaws 100 are thus in the positionsillustrated in FIGS. 5-7 wherein the horns 102, 104 engage and hold rimseats 22,20. The several jaws 100 are preadjusted employing screws 252(FIG. 11) during a set-up operation so that the average bead seat axisdefined by the engaged bead seat regions has a predeterminedrelationship to the axis of die reciprocation, either nominally coaxialor eccentrically offset therefrom by a predetermined amount and polardirection. The axis of the circle of bolt holes to be formed by punches56 is preferably co-incident with the axis of die reciprocation. Thus,the several jaws 100 locate the average bead seat axis coaxially withthe bolt hole circle axis, or place such average bead seat axis at aposition eccentrically offset from the axis of the bolt-hole circle by apreselected amount and direction in accordance with the teachings of theabove-referenced Daudi et al patents. With the wheel so fixtured by thelocating jaws 100 (FIG. 5), downward propulsion of upper die assembly 52is continued in an uninterrupted motion to and through the positionsillustrated in successive FIGS. 6-7.

As upper die assembly 52 is propelled downwardly from the position ofFIG. 5 toward the position of FIG. 6, the annular bosses 68 on upper diehead or stripper 64 engage the wheel disc around the several bolt holeislands 37, and thus cooperate with buttons 92 on lower die assembly 82to clamp the bolt hole islands against deflection and to hold the wheeldisc firmly against lower die mounting surface 90. With upper die head64 thus engaged with the wheel mounting disc (FIG. 5), continueddownward motion of upper die assembly 52 results in lost-motion of diebase 54 over die head 64 against the force of springs 66. Punches 56 arethus propelled through apertures in die head 64 so that the punch tips58 engage and pierce circular bolt openings in the fixtured wheel disc.Further downward motion of upper die assembly 52 brings punch conicalshoulders 62 into engagement with the outboard rim of the pierced boltholes so as to coin each of the pierced bolt holes. The several boltopening punches 56 are positioned on base 54 so that engagement ofabutment 256 against columns 258 corresponds to completion of thecoining operation on the pierced bolt openings.

Continued downward motion of upper die assembly 52 from the position ofFIG. 6, wherein piercing and coining of the bolt openings is completed,toward the position of FIG. 7 is transmitted to lower die assembly 82through columns 258. Lower die assembly 82 and locating jaws 100 mountedthereon thus move downwardly with respect to center column 74 againstthe force of springs 257 until base 84 abuts stops 255 (FIG. 11). Duringsuch downward motion, disc shoulders 40 are drawn downwardly against andover the upper outside edge of punch 76. The diameter of the punch edgeis greater than the preformed inside diameter of the disc shoulders, andin fact corresponds to the diameter of the wheel mounting hub (38 inFIG. 3) over which the wheel is to be mounted in use on a vehicle. Thus,punch 76 shears material from the disc shoulder to form lands 42, withexcess material being "plowed" to form ledges 43. The inside diameter ofthe interrupted circle of four lands 42 so sheared is accuratelypositioned and dimensioned for operation as a center-pilot opening.Shear punch 76 is designed either to located the axis of such landcircle inside diameter nominally coincident with the axis of column 74and thus with the bolt hole circle, and/or coincident with the averagebead seat axis, and/or eccentrically offset from one or both by apredetermined amount and direction. This may be accomplished by makingpunch 76 eccentric, such as punch 76a in FIG. 15, or by making the punchconcentric and mounting the same on a shim eccentrically adjustable oncolumn 74 to achieve differing positions of the center-opening axis,such as punch 76b and shim 76c in FIGS. 8-9 and 16. From the position ofFIG. 7, upper die assembly 54 is withdrawn vertically upwardly, withlower die assembly 82 returning to the rest position of FIGS. 4-6. Jaws100 are retracted and ring 99 lifts the wheel. The wheel may then bewithdrawn from the forming apparatus.

FIGS. 8 and 9 illustrate a modified apparatus 110 in accordance with theinvention for forming the bolt and center-pilot mounting openings in aso-called draw-neck-center wheel 112. In wheel 112 illustrated in FIGS.8 and 9, the flange 114 which surrounds and defines the preformed centeropening is terminated at about the level of the outboard surface of thebolt hole islands, and does not project outwardly therefrom to form ahub cone as in the styled wheel previously discussed. As best seen inFIG. 9, flange 114 is substantially circular, with radially inwarddepressions 115 being positioned between each bolt opening island andthe wheel axis. The structure and principles of operation of theapparatus 110 are similar to those previously discussed in detail inconnection with FIGS. 4-7, and need not be repeated. One importantfeature of the apparatus 110 illustrated in FIG. 8, which was notembodied in the apparatus of FIGS. 4-7, contemplates a scrap drop-outchute comprising a central bore 116 in swage punch 76b, which flaresoutwardly to the uppermost surface of the punch. Bore 116 is aligned inassembly with a central bore 118 in column 74a. Thus, in the embodimentof FIGS. 8 and 9, the material which is sheared from the inside diameterof the center opening flange depressions 115 will fall by gravitythrough chute openings 116,118 for disposal.

FIGS. 11-12, in addition to illustrating the overall die arrangement forthe apparatus hereinabove discussed, also illustrate modified punchingmeans for an embodiment of the styled wheel having five bolt holes, asdistinguished from the four-hole embodiment of FIGS. 1-3. Elements ofthe apparatus of FIGS. 11--12 which correspond to those hereinabovediscussed in detail possess identical reference numerals. Die head 64 inthe embodiment of FIGS. 11-12 includes a circumferential array of pinpairs 260 biased downwardly with respect to die base 54 by the springs262 for reception into the disc openings 261 and engagement withangulated edges of spaced openings 261 (FIG. 1) in the preassembled rimand disc, and thereby locating and holding the disc preformcircumferentially with respect to the forming apparatus. Swage punch 76ahas an annular stripper ring 264 affixed thereto axially upwardly of theswaging edge of punch 76a, stripper ring 264 having an outside diameterwhich is slightly less than that of the swaging punch edge. The purposeof stripper 264 is to remove ledges 43 (FIG. 10) sheared from the discID as the rim and disc assembly is withdrawn upwardly from punch 76a,and to direct such material downwardly through the center openings 266in swage punch 76a and column 74.

FIG. 13 is an enlarged view which illustrates the apparatus of FIGS.11-12 in the fully closed position (corresponding to FIG. 7). Thecontour 68 of die head 64 is such as to produce line contact with disc24 surrounding bolt hole island 37, leaving radial clearance bothinwardly and outwardly. In the same way, buttons 92 on lower dieassembly 82 axially engage the inboard surface of bolt hole islands 37,but are dimensioned radially for clearance with respect to the discmaterial. In addition, the zones of disc 24 thus contacted by die head64 and buttons 92 have at least a limited planar surface extendingperpendicular to the disc axis. Thus, in accordance with an importantfeature of the invention, the disc-engaging surfaces of the upper andlower die assembly accommodate limited radial bodily motion of the rimand disc assembly, i.e., lateral shifting or sliding of the preform inthe die set, upon closure of jaws 100 for accurate location of theaverage bead seat axis under control of jaws 100 without stressing therim or disc.

FIG. 14, which is a flow diagram illustrating the sequence of operationson the rim and disc assembly, illustrates another important feature ofthe present invention. That is, between each operation on the rim anddisc assembly--i.e. chucking or fixturing the rim by closure of jaws 100(FIG. 5), punching and coining the bolt holes (FIG. 6 or 11), andshearing the center hole (FIG. 7 or 13)--there is a limited idle period.This idle time, which is on the order of tenths of seconds, permits therim and disc assembly to settle prior to the next operation. Inclusionof the idle times as illustrated in FIG. 14 has been found to be verybeneficial in terms of accurately locating the various wheel axes ashereinabove described. Most preferably, the idle periods are built intothe forming apparatus as lost motion in a continuous movement of theupper die assembly with respect to the lower die assembly.

FIG. 15 is a plan view of swage punch 76a in FIG. 11. It will be notedin particular that the axis or centerline 270 of the swage mountingopenings 272 is laterally eccentric or offset from the axis 273 ofswaging edge 274 by the predetermined amount 276. Thus, with swage punch76a mounted on column 74 and a rim and disc assembly propelleddownwardly thereagainst, the axis of the center hole will correspond toaxis 273 of edge 274 and be eccentrically offset from axis 270 of punch76a and column 74 by the amount 276. At the same time, the average beadseat axis is offset a predetermined amount from the axis of column 74 byadjustment of jaws 100, so that total eccentricity of the center holewith respect to the average bead seat axis is determined by these twooffsets. Most preferably, a number of punches 76a are provided havingdiffering predetermined eccentricities 276 for selective assembly tocolumn 74 as desired. Of course, at least one punch 76a in the set ofpunches should possess zero eccentricity 276--i.e. have axes 270,273coincident--so that the disc center-hole axis will coincide with theaxis of column 74 and the center of the disc bolt-hole circle.

FIG. 16 illustrates swage punch 76b of FIGS. 8 and 9. In swage punch76b, the axis of mounting openings 272 and swage edge 274 are coincidentwith the axis of center opening 278. However, a shim 76c, which ismounted between punch 76b and column 74, has a circumferential array ofarcuate mounting slots 280 on a common circle having a center 282 whichis offset from or eccentric to the axis 284 of the shim center opening286. Swage punch 76b has a depending center boss 288 (FIG. 8) which isslidably received with a precision fit in shim center opening 286. Thus,amount and angle of eccentricity of swaging edge 274 of punch 76b isadjustable with respect to the axis of column 74 by loosening the swagepunch mounting bolts 77 (FIG. 8) and adjusting shim 76c angularly of thecolumn axis, openings 272 in punch 76b being sufficiently oversize topermit limited lateral motion of punch 76b with respect to bolts 77(FIG. 8) and column 74a. It will be noted that shim 76c rests in acounterbore on the upper surface of column 74b to prevent radial motion,and that boss 288 (FIG. 8) has a close fit with center opening 286 ofshim 76c. These close fits hold radial precision, bolts 77 servingmerely to clamp punch 76b and shim 76c from the axial direction.

FIGS. 17A and 17B illustrate operation of apparatus in accordance withthe present invention for selectively and adjustably positioning thebolt-hole and center-hole axes with respect to average bead seat axes.Each of the FIGS. 17A and 17B are polar diagrams which illustratemagnitude of eccentricity of center-hole axes CH and bolt-hole axes BHwith respect to average bead seat axis BS for a number of test wheels.FIGS. 17A and 17B also illustrate the angle of such eccentricities withrespect to a line from the average bead seat axis BS to the disc valvehole VH. Each of the FIGS. 17A and 17B indicate location of center-holeaxes and bolt-hole axes for a number of test wheels with respect to afirst tolerance limit 292, which corresponds to an industry standardwheel specification 5.1.8 set by General Motors Corporation, and asecond tighter tolerance standard 294 set by applicant's assignee. InFIG. 17A, both the center-hole axes CH and the bolt-hole axes BH areclustered within the tolerance specification 294. The axis of the disccenter opening may be varied by adjusting angular orientation of shim76c (FIGS. 8 and 16), or by selecting an appropriate swage punch 76a(FIGS. 11 and 15), so as to move the center-hole axes closer to thebolt-hole axes. Thus, the bolt hole axes, which are nominally concentricwith the axis of column 74, are not adjusted, and the average bead seataxes BS which is determined by adjusted location of jaws 100 withrespect to column 74 are not varied. Rather, the center-hole axes arepositioned more closely to the axis of column 74, and thus more closelyto the bolt-hole axes. The results are illustrated in FIG. 17B whereinboth the center-hole axes CH and the bolt-hole axes BH are withinspecification 294 with respect to the average bead seat axis BS andangular orientation of valve hole VH, and are also closer to each other.

FIGS. 18-20 illustrate a modification to the styled wheel of FIGS. 1-3for enhancing accuracy of center hole location. More particularly, anindentation or ledge 296 is struck radially inwardly on each shoulder 40of disc hub cone 32. As the wheel disc is propelled downwardly over theswage punch, the punch shears material from indentations 296 to formshoulders 298 (FIG. 20) on a common cylinder of revolution which definesthe center hole axis. By deforming indentations 296 rather than the bodyof shoulders 40 as in the embodiment of FIGS. 1-3 and 10, elasticdeformation of the shoulder during the swaging process, and consequentmispositioning of the disc center hole axis, is significantly reduced.The draw-neck wheel illustrated in FIGS. 8 and 9 includes similarindentations 115.

The foregoing description teaches a specific presently preferred methodfor "forming" the bolt and center-pilot mounting openings and severalembodiments of apparatus for performing such method. Specifically, thebolt openings are pierced and coined, and the ID of the center-pilotopening is shear-formed. However, the term "forming" encompasses other,albiet less preferred, methods such as drilling, milling or boring whereappropriate.

The invention claimed is:
 1. Apparatus for forming bolt and center pilotopenings in a preformed vehicle wheel which includes a rim having a tirebead seat region and a wheel mounting disc having a preformed centeropening carried internally of said rim, said apparatus comprisinga fixedsupport, a column mounted on said fixed support and defining a columnaxis, a first die assembly mounted on said support surrounding saidcolumn for reciprocation along said axis with respect to said column andsupport, said first die assembly including support means for axiallysupporting one face of a wheel disc surrounding said preformed centeropening while leaving said wheel free to move radially of said axis, acircumferential series of locating means carried in a planar array bysaid first die assembly for radial reciprocation with respect to saidcolumn axis, a second die assembly opposed to said first die assembly,and including means for engaging a face of said disc opposed to said oneface and means for forming said bolt openings in said disc on a boltopening axis coincident with said column axis, means depending from saidsecond die assembly for engaging and reciprocating said locating meansradially inwardly toward said axis to engage and hold the bead seatregion of a wheel in said apparatus, said locating means including meansfor radial positioning each of said locating means so as to engage saidbead seat region without plastic deformation to said bead seat region,said support means being constructed for engaging said one disc facewhile permitting lateral motion of said wheel upon engagement by saidlocating means to locate said bead seat region on a bead seat axis atpreselected position with respect to said column axis without plasticdeformation of said rim or said disc, lateral positioning of said beadseat axis with respect to said column axis being determined solely bysaid locating means, means carried in fixed position on said centercolumn and having a predetermined diameter greater than the diameter ofsaid preformed center opening for shear-swaging enlargement of saidpreformed center opening on a center-opening axis at preselectedposition with respect to said column axis, and means for propelling saidsecond die assembly in the direction of said column axis in a continuousmotion for first engaging and reciprocating said locating means intoengagement with the bead seat of a wheel to position the bead seat axis,for thereafter forming said bolt openings, and for thereafter movingsaid wheel and said first die assembly conjointly with each other alongsaid column to bring said preformed center opening into shearingengagement with said shear-swaging means, said shear-swaging means beingsized to form said center opening by shear-removal of material from saiddisc around said preformed opening, said column, said first and seconddie assemblies and said locating means being constructed for lost motionof said second die assembly with respect to said column, said first dieassembly and said locating means between engagement of said locatingmeans and forming said openings, and between forming said bolt openingsand shear-swaging said center opening.
 2. The apparatus set forth inclaim 1 wherein said first die assembly includes a die base having aplurality of punches affixed thereto and projecting axially therefrom ina circular array about said column axis to pierce said bolt openings, adie head mounted for axial movement on said die base, means biasing saiddie head with respect to said base in the direction of said planararray, and stop means for limiting motion of said head against saidbiasing means, said stop means being so positioned with respect to saidpunches and said base that said bolt openings are pierced and formed bysaid punches prior to engagement of said stop means.
 3. The apparatusset forth in claim 1 wherein said preformed disc center opening iscircumferentially surrounded by an axially extending flange having anarray of angularly spaced indentations projecting radially inwardlytherefrom, said indentations defining circumference of said centeropening, and wherein said means for shear-swaging said center openingincludes means for shear-removal of material from said indentationswithout plastic deformation of said flange or said disc.
 4. Apparatusfor forming bolt and center-pilot openings in a preformed vehicle discwheel which includes a wheel rim having a radially outwardly facing tirebead seat region and a wheel disc having a preformed center openingsurrounded by an axially extending flange mounted internally of saidrim, said apparatus comprisinga circumferential array of locating meansdisposed in a planar array for selectively radially engaging and holdingsaid bead seat region centered on a first axis without plasticdeformation to said bead seat region, a first die assembly mounted onone side of said planar array for reciprocation in the direction of saidfirst axis, said first die assembly including a die base havingcircumferential series of bolt opening punches fixedly projecting in theaxial direction toward said array about a second axis and a die headsurrounding said punches for abutting engagement with an opposingsurface of the wheel disc, and means for axially engaging said locatingmeans and moving said locating means into engagement with said bead seatregion, a second die assembly mounted on the opposing side of saidplanar array for engaging and holding said disc against deflection fromsaid first die assembly, disc-engaging portions of said first and seconddie assemblies including means for permitting lateral motion of saidpreformed wheel when engaged by said locating means, a column fixedlypositioned at one end and extending through said second die assembly toa second end, with a center-pilot opening punch being mounted on saidsecond end for shear-punching said disc center opening on a third axis,means mounting said locating means on said second die assembly forconjoint motion axially of and guided by said column, and means forpropelling said first die assembly in said direction of said first axisin a continuous uninterrupted motion toward said array so that saidlocating means are closed against the bead seat region of a wheel onsaid second die assembly, said bolt openings are formed on said secondaxis in the disc of a wheel engaged and held on said first axis by saidlocating means, followed by conjoint motion of said first and second dieassemblies and said disc against said center punch for shearing saidflange inside diameter on said third axis to form said center pilotopening.
 5. The apparatus set forth in claim 4 wherein said locatingmeans include means for selectively positioning said first axis withrespect to said second axis, and wherein said center punch includesmeans for selectively positioning said third axis with respect to saidsecond axis.
 6. The apparatus set forth in claim 4 wherein said die headis mounted for axial movement on said die base and wherein said firstdie means further comprises means normally biasing said die head towardsaid planar array, said die head and biasing means being such that saiddie head engages the disc of a wheel held by said locating means priorto engagement of said bolt opening punches with said disc, and stopmeans for limiting motion of said die head against said biasing means,so that further motion of said die base is transmitted to said seconddie means and said locator means through said stop means, die head andwheel disc.
 7. The apparatus set forth in claim 6 wherein said preformeddisc center opening is circumferentially surrounding by an axiallyextending flange having an array of angularly spaced indentationsprojecting radially inwardly therefrom, said indentations definingcircumference of said center opening, and wherein said center-pilotopening punch includes means for shear-removal of material from saidindentations without plastic deformation of said flange or said disc.